Hay Walls are invisible when placed. When attempted to use hammer, got "go for the eyes!" and three or four hits. Screenshot taken after that. Uninstalled and reinstalled last Saturday to attempt to fix issue. Google Pixel 3 XL with Android 9.
My Printing Pod gave me a care package of 3 slickster eggs. After many turns they grew up into Slicksters and all was well. I exited, and when I came back to it (autosave), my Slicksters had disappeared. The oil they exuded is still there. The Drecklet that grew up into a Drecko (also care package) is still there. The Wort and other care package seeds are still there. So it doesn't seem to be a care package issue but rather a Slickster issue.